Cannot login to Service desk 7.5

I have Upgraded to V7.5
ran this with no issues for a few days, so i ran a Asset Scan - which seemed to work
I logged out and back in again, finding that i could not log into the service desk.
Other people have been complaining also.
One tech was able to log in, So with his account, i reset my technical details - and tried again, still not working
I then deleted my account, and ran an AD Scan to get my userid back in as a requestor. I noticed i had to reset the AD Details, finally allowing me to add my userid to the requestor field. I then assigned myself as a technician, and ticked the box for LDAP Authentication.

Now NO ONE Can log into the site...

I have 5 technicians and over 200 requestors.
Im getting hammered to get this fixed -

Is there a way to RESET the domain details as ive also noticed that our domain name has changed to CO ?????
Also ive tried to do a restore from yesterdays backup - still not working......

Please help